The present invention relates to a method of adjusting a beam condition for a charged particle beam and a charged particle beam apparatus and more particularly, to a method of making astigmatism correction, focus correction and FOV (field of view) shift correction when giving the beam a tilt.
In the charged particle beam apparatus represented by a scanning electron microscope, a charged particle beam is focused to a fine beam which in turn is scanned on a specimen to obtain desired information from the specimen (for example, a specimen image). In the charged particle beam apparatus as above, the resolving power becomes higher year by year and besides, recently, there is a growing need for obtaining a tilt image of a specimen by tilting a charged particle beam in relation to the specimen. This is accounted for by the fact that for acquisition of tilt images of the specimen, it is general to tilt a specimen stage but for the purpose of preventing a FOV shift at high magnification and acquiring a tilt image of the specimen more speedily, giving the charged particle beam a tilt in relation to the specimen is more rational than mechanically tilting the specimen stage.
A technique for irradiating a beam while tilting it is known as described in Patent Document 1 (JP-A-55-048610 (U.M.)) or Patent Document 2 (U.S. Pat. No. 4,983,832 corresponding to JP-A-02-033843), for instance. In the known technique, a charged particle beam is caused to be incident on a region which is out of axis of an objective lens and is then tilted using the focusing action (Imaging Action) of the objective lens.